Pole and method of constructing same



UNITED STATES PATENT OFFICE.

ROBERT L. ALEXANDER, OF WEST ALLIS, WISCONSIN, ASSIGNOR TO ALLIS-CHALMERS MANUFACTURING COMPANY, OF MILWAUKEE, WISCONSIN, A CORPORATION OF DELAWARE.

POLE AND METHOD OF CONSTRUCTING SAME.

Patented Mar. 1, 1921.

Application led August 28, 1918. Serial No. 252,126.

To ZZ/07101724115 'may concern Be it known that l', ROBERT 1li. AmixANnnn, a citizen of the United States, residing at West Allis, in the county of Milwaukee and State of lVisconsin, have invented a certain new and useful Improvement in Poles and Methods of Constructing Same, of which the following is a specification.

This invention relates to magnetic field structures and the pole pieces thereof and a method of constructing the same. The invention may be applied in dynamo-electric machines and a particularly advantageous use of the invention is in large alternating current generators having revolving field structures.

In large machines in which revolving magnetic field structures are used having projecting pole pieces very considerable stresses arise chiefly by reason of centrifugal forces tending to pull the pole pieces away from the core in which they are fastened. It is usual to construct such pole pieces with a plurality of means for fastening the same to the core in order to give sufficient strength to resist the forces developed. One ofthe difficulties encountered in such a construction is that with the ordinary accuracy of workmanship the various fastening means do not assume the same share of the stresses developed' and it has been proposed to construct pole pieces divided in several parts each one having its own individual fastening means. `Here again it may occur that due to variations in accuracy of workmanship the various parts of the divided pole will'not extend parallel to each other or in the desired relative directions as the case may be, and it is one of the objects of this invention to provide a method and means which will obviate these undesirable features.

Another object of the invention is the provision of a method and means for balancing centrifugal stresses arising in the pole tips where such are provided on the projecting pole pieces.

Another object of the invention is the provision of aV method and means whereby such pole pieces may be cheaply and expeditiously manufactured. Other objects will yappeal' hereinafter as the description proceeds.

...Mmmmmwmmamwi The novel features of the invention will appear from this specification and the accompanying drawings which form a part thereof and all. these novel features are intended to be particularly pointed out in the claims.

in Figure 1 is shown a field structure embodying the features of the invention, a

fragment only of the revolving core being shown.

Fig. 2 shows a side elevation of one of the divided parts of the pole piece, the coil and core being shown in section along the line II-IL Fig.v 3 shows a modification of Fig. 2.

The proj eoting pole piece of the revolving field structure is illustrated in F ig. l as being built up out of two independent symmetrical halves 2, 3 fastened to the core 1 of the revolving field. Each half of the pole is provided with an end plate 4 at one end and a similar one 5 at the other end for holding the sets of laminae 6 together. Fastening means of any7 desired form, as bolts T, ma;7 be used.r The pole halves 2, 3 are provided with dovetail projections ,8, 9 lvhich are adapted to cooperate with dovetail slots in the core l and to be held therein by means of wedges or keys 10, 11. It is however obvious that it is not necessary as far the present invention is concerned that dovetail means be used for fastening the pole halves to the core and that any other suitable means may be employed.

The pole halves 2, 3 are preferably but l not necessarily so constructed and related to each' other that when they are assembled on the core l they will be juxtaposed but spaced apart to a desired extent. This slight spacing is to allow for any slight inaccuracy in the construction of the pole halves whereby the juxtaposed faces would not be precisely parallel.

The two pole halves 2, 8 may be provided with slots, cuts or recesses which when the pole halves are assembled, register to form hole 12; or this hole may be made wholly by drilling or boring. VA spacing means here shown as a dowel or wedge 13 is shown as inserted in the hole 12 and is preferably a driving fit. The term spacing means as used in the lclaims is intended to cover a means which serves either to merely keep the. spaced parts from approaching each other a predeternnned extent or to spread thein apart, or both. For the salte of brevity the spacing means lll will be hereinafter referred to as a dowel. Alifter the dowel 13 is driven into the hole l2 the end plate, as for example el, may be peened over as shown at l5. rlhe end plates iiay be cored out or in any other manner constructed so as to 'Forni a coui'iter-sunl portion 1T. ln the Yform of the invention shown in Fig. 2 two dowel pins 13 are used oi any desired length. rl'he laininae (5 may be provided with notcher4 il so that when theVT are assembled in reggisthey Jforni a portion oi the hole l2. A slightly lai-pier diameter then l any suitable manner into each end L the pole hallE throupji the end plate into the laininre, the drill being selected so that the doivel pins i3 will snugly lit the hole. .is previously noted the dowel pins 13 may be held in the holes by any suitable ineans such as peenin` over the end plates.

T he hole l), `pre'terablv near the air gap end oi the l 's pole halves and it 1 to be understood that this location includes any one wher the wedge or dowel will periorm its desired functions.

lt is however not necessary that two dowels should be used and as shown in Figi. 3 a hole may be bored through troni one e d ot tie pole to the other and but a single dowel be used.

Pole pieces as above describet are usuallv shipped and handled with the encre coil surroundingthe pole halves l in order to prevent the pole halves slippingrelatively to each other when so handledfas for e1;- ainple ii a hold is taken on only one of the dovctail proiections. si" all dowel pins lt are provided et y desired iiuinber. These dowel pins are co iientlif' inserted in holes in the siees ot the end plates as clearly shown.

lt `will be noted that with the pole and method ot constructing;` the saine herein described possible to have each pole hallz y fastened to the revolving the transmis-:ion oli fastening Joni one pole part to the other d yet to have the pole parts in intimate contact the air gap end so that any unbalanced stresses arising` in the twoU pole parts will ri a f t cach other.

it should be unf, ood that it is not desired that the iuveniion claimed be limited to the e: 1; details et construction as shown and described For obvious modifications inav occur o persons "l illed in the art. i

is claimed nd desired to secure bv `rs Patent: L

l. The method ot constincting` a pole piece comprising at least two parts which consists in fastening each partseparately to a com nion support so that the parts are in juxtaposition but spaced apart and then inserting; at least one spacing` ineans between said parts near the air gap end oi said parts.

The method of constructiin.;- a pole piece coniprisinif;- at least two parts, which consists in fastening cach part separately to a coinnion support so that the parts are adjacent each other, then boring` at least one hole between said parts near the z'r gap end and then insertingat least one spacing' means in each hole.

ln coinbinatioin a coro, a pole for said coro comprising a.. plurality ot' parts adje reef" to and spaced 'from each other and al one spacing means between said paris near the air gap end.

l. ln combination, a core, a pole i'or coril comprising a plurality olf parts juliand spaced apart7 'l parts havingV tering slots in the iuxtaptsel 'tacos and least one spacingmeans in said registerln combination, a core7 a polo for said core comprising' a plurality ol' parts jin; 1aposed and spaced apart, each part compris ingr a set of laminze and end plates, said end plates having registering .slot-s in the juxtaposed faces and at least one spacing means in said registering slots.

6. In combination, a core, a pole for said core coinprisinp` a plurality oit parts adjacent each other, means ior fastening each part separately to said core, and at least one spacing means between said parts near the air gap end.

Y. lu combination, a substantially cylindrical core. a pole for said core comprisingl a plurality oi' parts, means for fastening each of said parts separately to said core at different circumferential points, and at least one spacing means between said parts near the air end.

8, 'in combination, a core, a pole for said core comprising a` plurality of adjacent parte, saitL parts having registering slots in the adjacent faces, means `for fastening each part separately to said core, and at least one spacing means in said registeringl slots.

9. .in combination, a core` a pole for said core comprising a plurality of adjacent parts, each part comprising a set of laininze and end plates, said end plates having reg-- istering' slotsin the adjacent faces7 means for fastening each part separately to said core, and at least one spacing means in said registering slots.

l0. In combination, a substantially cylindrical core, a pole tor said core comprising a plurality of adjacent partsq each part cornprising a. set of laininze and end plates, said end plates having registering slots, means `for fastening` each part separately to said core and at least one spacing means in said registering slots.

l1. In combination, a substantially cylindrical core, a pole for said core comprising a plurality of adjacent parts, each part comprising a set oi laminae and end. plates, said end plates having kregjfistering slots means iter fastening each of said parts sepam rately to said core at diiierent circumferen tial points, and at least one spacing means in said registering slots. f

l2. In combination, a substantially cylindrical core7 a pole for said core comprising a plurality of adjacent parts, said parts having registering slots in the adjacent faces, means for 'fastening each of said parts separately to said core at different circumferential points and at least one spacing means in said registering slots.

1,3. A structure comprising a pole piece having separate parts, a coil surrounding said parts, and means comprisin atleast one comparatively loosely fitting do posed in and transversely between said parts whereby relatively great movement of said parts in the general direction o' the axis oi said coil is prevented.

la. In combination, a core, a pole for said core comprisinga plurality of adjacent parts, means for fastening each of said parts separately to said core and separate means associated with lootli of adjacent pole parts for equalizing bending stresses arising in said parts.

l5. In combination, a substantially cylindrical core, a pole `for said core comprising a. plurality of adjacent parts7 means for fastening each of said parts separately to said core at diiferent circumferential points and separate means associated with both of adjacent pole parts for equalizing bending stresses arising in said parts.

In testimony whereof, the signature of the inventor is aiixed hereto.

ROBERT L. ALEXANDER. 

